Destroying undesired vegetation with halobenzylcarbamates



Ill

6 Claims. (Cl. 712.3)

This application is a division of application Ser. No. 55,111 filed Sept. 12, 1960, now abandoned.

The present invention relates to new halobenzyl esters of the general formula where X is halogen, n is 2 or 3 and R is an amino radical. The halogen substituents are preferably chlorine but bromine and to a lesser extent fluorine and iodine are also suitable. When n is 2, compounds containing halogen in the 2,5- and 2,6-positions are preferred. Examples of amino radicals are disubstituted NH wherein the substituents may be lower alkyl, alkoxy substituted lower alkyl, lower olefinic, halogen substituted lower olefinic and cycloalkyl with the proviso that not more than one is cycloalkyl and radicals derived by removal of the hydrogen from the nitrogen of pyrrolidine, piperidine, hexamethylenimine and lower alkyl substituted derivatives thereof. Cyclohexyl is the preferred cycloalkyl group but cyclopentyl and lower alkyl substituted cyclohexyl and cyclopentyl radicals confer similar properties. These compounds are useful for destroying or retarding undesired vegetation. Furthermore, they are useful as toxic constituents in fungicidal compositions. In addition, they are useful adjuvants for the compounding of mineral lubricating oils. They are readily soluble in mineral oil fractions and have the property of increasing the load carrying capacity of mineral oil lubricants. Additionally, these compounds are useful as intermediates. For example, amides result from condensation with amines.

The halobenzyl esters of this invention may be prepared by condensing a halogenated benzyl alcohol with a carbonyl halide. The compounds designated ar,ar,ar-trichlorobenzyl esters were derived from reaction of a carbonyl halide with a mixer isomer of a halogenated benzyl alcohol containing an average of three halogen atoms in the carbocyclic ring prepared by the following procedure: Substantially 1500 parts by weight of dry toluene was charged into a chlorinator of suitable capacity. Substantially parts by weight of iron filings were added as catalyst carrier for ring chlorination and chlorine introduced at about C. During the last part of the run the temperature was increased to about 70 C. in order to keep the reaction mixture fluid and the flow of chlorine continued until the increase in weight corresponded to that calculated for trichlorotoluene. Thus, when the product analyzed 54.8% chlorine, the flow of chlorine was interrupted and the trichlorotoluene given a 10% caustic wash and filtered through a bed of clay in order to remove the iron. Substantially 415 grams (2.12 moles) of trichlorotoluene thus prepared was charged to a 1-liter flask and heated to 150 C. A sunlamp was placed about 8 inches from the fiask to activate bromination. Substantially 339 grams (4.45 moles) of bromine was fed in below the surface over a 60 minute period at 150160 C. The product was allowed to cool over night and then vacuum treated under mm. pressure. Trichlorobenzyl bromide was obtained in theory yield.

Substantially 452 grams (1.59 moles) of the trichlorobenzyl bromide was charged to a reactor with 169 grams W. Va., assignor to Mon- Mo., a corporation of Delad States Pater (1.59 moles) of sodium carbonate and 1510 grams of water. The mixture was heated at refluxing temperature (95100 C.) for 72 hours. After cooling to 25 C., salt was added to saturate the solution and salt out the upper product layer which was then separated and extracted with ether. The ether was removed by distillation in vacuo at a maximum temperature of 90 C./5-10 mm. ar, ar,ar-Trichlorobenzyl alcohol was obtained in 97.5% yield as an oil which solidified on standing. Analysis gave 51% chlorine as compared to a calculated value of 50.4% chlorine.

As illustrative of the new compounds and their method of preparation, the following examples are given:

Example 1 To a mixture of 21.1 grams (0.1 mole) of the ar,ar,artrichlorobenzyl alcohol prepared as described above, 4 grams (0.1 mole) of sodium hydroxide and 100 ml. of acetone there was added dropwise with stirring over a period of 10 minutes 19 grams (0.1 mole) of N-cyclohexyl N-ethyl carbonyl chloride. The reaction mixture was then heated at 5056 C. for 6 hours. After cooling to 25 C., 250 ml. of water and 300 ml. of ethyl ether were added and stirring continued for 15 minutes. The ether solution was washed with water until neutral to litmus, dried over sodium sulfate and the ether removed in vacuo at a maximum temperature of 80-90 C./12 mm. ar,ar,ar-Trichlorobenzyl N-ethylcyclohexanecarbamate was obtained as a tan semi-solid in 82.0% yield. It was soluble in ether, acetone, benzene, heptane and ethanol but insoluble in water. Analysis gave 3.2% nitrogen compared to 3.8% calculated for C H Cl NO Example 2 To a stirred solution comprising 21.1 grams (0.1 mole) of the aforedescribed mixed isomer of trichlorobenzyl alcohol, 100 ml. of ethyl acetate and 12 ml. of triethylamine there was added in one portion 13.6 grams (0.1 mole) of diethyl carbonyl chloride. The mixture was then heated and maintained at reflux temperature for 5 hours. After cooling to 25 C., 100 ml. of water was added and stirring continued for 15 minutes. The top ethyl acetate layer was washed with water until neutral to litmus and dried over sodium sulfate. The solvent was removed in vacuo at a maximum temperature of 8090 C./12 mm. ar,ar,ar-Trichlorobenzyl diethylcarbamate was obtained as a semi-solid in yield. It was soluble in acetone and ethanol, slightly soluble in ether and benzene but insoluble in heptane and water. Analysis gave 4.6% nitrogen compared to 4.5% calculated for C H Cl NO Example 3 To a stirred solution comprising 52.9 grams (0.25 mole) of the mixed isomer of trichlorobenzyl alcohol described, 35 grams (0.25 mole) of potassium carbonate and 300 ml. of heptane was added in one portion 30.9 grams (0.25 mole) of pyrrolidinyl carbonyl chloride. The mixture was then heated and maintained at reflux temperature for 6 hours, filtered hot and the solvent removed in vacuo at a maximum temperature of 8090 C./12 mm. ar,ar,ar-Trichlorobenzyl 1-pyrrolidinylcarboxylate was obtained as an amber oil in 87.0% yield. It was soluble in ether, acetone, benzene, heptane and ethanol but insoluble in water.

The mixed isomer of trichlorobenzyl alcohol described and the general procedure of Example 3 were used in Examples 4-9. The products were all amber oils possessing the same solubilities as in Example 3.

Example 4 ar,ar,ar-Trichlorobenzyl l-piperidinecarboxylate was obtained from l-piperidinylcarbonyl chloride in 99.5% yield.

3 Example 5 ar,ar,ar-Trichlorobenzyl N,N bis(2-chloroallyl)carbamate was obtained from bis(2-chloroallyl)carbonyl chloride in 99.5% yield.

Example 6 ar,ar,ar-Trichlorobenzy1 N,N-diallylcarbamate was obtained from diallyl carbonyl chloride in 99% yield.

Example 7 ar,ar,ar-Trichlorobenzyl N allylcyclohexanecarbamate was obtained from N-allylcyclohexyl carbonyl chloride in 95.5% yield.

Example 8 ar,ar,ar-Trichlorobenzyl diisopropylcarbamate from diisopropyl carbonyl chloride in 97.5% yield.

Example 9 ar,ar,ar-Trichlorobenzyl N-(Z-chloroallyl)cyclohexanecarbamate from N-(2-chloroallyl)cyclohexyl carbonyl chloride in 73% yield.

Example 10 To a stirred solution comprising 44.3 grams (0.25 mole) of 2,6-dichlorobenzyl alcohol and 300 ml. of benzene was added 34 grams (0.25 mole) of diethyl carbonyl chloride. While stirring the mixture it was heated and maintained at refiux temperature for 18 hours. After cooling to C., 200 ml. of Water was added and stirring continued for 15 minutes. The benzene layer was washed with water until neutral to litmus and dried over sodium sulfate. Benzene was removed in vacuo at 8090 C./1-2 mm. The residue was a semi-solid obtained in 94% yield. After drying on a porous plate 2,6-dichlorobenzyl diethylcarbamate was obtained as a white solid, M.P. 58- 60 C. Analysis gave 5.1% nitrogen and 25.5% chlorine as compared to 5.1% nitrogen and 25.7% chlorine calculated for C12H15C12NO2.

Example 11 To a stirred solution comprising 17.7 grams (0.1 mole) of 2,5-dichlorobenzyl alcohol, 150 ml. of heptane and 13.9 grams (0.1 mole) of potassium carbonate was added in one portion 19 grams (0.1 mole) of N-cyclohexyl N- ethylcarbonyl chloride. The mixture was then heated and maintained at reflux temperature for 6 hours, filtered hot to remove salt and the solvent removed in vacuo at a maximum temperature of 80-90 C./12 mm. 2,5-dichlorobenzyl N-ethylcyclohexanecarbamate was obtained as an amber oil in 94% yield. Analysis gave 4.0% nitrogen compared to 4.2% calculated for C H Cl NO Example 12 Substituting 2,6-dichlorobenzyl alcohol for the 2,5-dichlorobenzyl alcohol in the procedure of Example 11 gave 2,6 dichlorobenzyl N ethylcyclohexanecarbamate in 93.9% yield. The product solidified on standing. After drying on a porous plate it was a tan solid, M.P. 162-164 C. Analysis gave 22.0% chlorine as compared to 21.5% calculated for C H Cl NO Other examples are recorded below. These are merely cited further to illustrate the invention and variations will be evident to those skilled in the art:

ar,ar,ar-trichlorobenzyl dibutylcarbamate ar,ar,ar-trichlorobenzyl dipropylcarbamate ar,ar,ar-trichlor-obenzyl diisopropylcarbamate ar,ar,ar-trichlorobenzyl N-(methoxypropyl) cyclohexanecarbamate ar,ar,ar-trichlorobenzyl N-(methoxyethyl) cyclohexanecarbamate ar,ar,ar-trichlorobenzyl N-allyl N-rnethoxypropylcarbamate ar,ar,ar-trichlorobenzyl N-allyl N-methoxyethylcarbamate ar,ar,ar-trichlorobenzy1 N,N-bis(methoxyethyl) carbamate ar,ar,ar-trichlorobenzyl N,N-bis(methoxypropyl) carbamate ar,ar,ar-trich1orobenzyl N,N-bis (methoxybutyl) carbamate ar,ar,ar-trichlorobenzyl N,N-bis (ethoxyethyl) carbamate ar,ar,ar-trichlorobenzyl l-hexan1ethyleniminecarboxylate ar,ar,ar-trichlorobenzyl 5-ethyl-2-methylpiperidinecarboxylate ar,ar,ar-tricl1lorobenzyl 2-1nethyl-l-piperidinecarboxylate 2,6-dichlorobenzyl l-pyrrolidinecarboxylate 2,5-dichlorobenzyl 1-pyrrolidinecarboxylate 2,6-dichlorobenzyl l-piperidinecarboxylate 2,5-dichlorobenzyl l-piperidinecarboxylate 2,6-dichlorobenzyl 2-methyl-l-piperidinecarboxylate 2,6-dichlorobenzyl S-ethyl2-methylpiperidinecarboxylate 2,6-dichlorobenzyl 1-hexamethyleniminecarboxylate 2,5-dichlorobenzyl l-hexamethyleniminecarboxylate 2,6-dichlorobenzyl N-(methoxypropyl) cyclohexanecarbamate 2,6-dichlorobenzyl N-(methoxyethyl)cyclohexanecarbamate 2,6-dichlorobenzyl N-allyl N-methoxypropylcarbamate 2,5-dichlorobenzyl N-allyl N-methoxyethylcarbamate 2,5-dichlorobenzyl N,N-bis(methoxyethyl) carbamate 2,6-dichlorobenzyl N,N-bis(methoxyethyl) carbamate 2,6-dichlorobenzyl N,N-bis(eth0xyethyl)carbamate 2,6-dichlorobenzyl N,N-bis(ethoxybutyl)carbamate 2,4,5-trichlorobenzyl diethylcarbamate 2,4,5-tribromobenzyl diethylcarbamate 2,4,6-trichlorobenzyl dipropylcarbamate 2,4,6-tribromobenzyl dipropylcarbamate 2,3,6-trichlorobenzyl diethylcarbamate 2,3,6-tribromobenzyl diethylcarbamate 2,3,4-trichlorobenzyl diethylcarbamate 2,3,4-tribromobenzyl diethylcarbamate 2,3,5 -trichlor0benzyl diethylcarbamate 2,3-dichlorobenzyl diethylcarbamate 3,4,5-trichlorobenzyl diethylcarbamate Herbicidal compositions may be prepared by admixing the ester with a carrier material in order to provide for mulations adapted for ready and etficient application in liquid or solid form. Solid compositions are formulated by mixing the toxicant with a finely divided or granular solid, as for example tricalcium phosphate, calcium carbonate, kaolin, bole, kieselguhr, talc, bentonite, fullers earth, pyrophyllite diatomaceous earth, calcined magnesia, volcanic ash, sulfur and the like inorganic solid materials, and include for example, such materials of organic nature as powdered cork, powdered wood, and powdered walnut shells. The preferred solid carriers are the adsorbent clays, e.g. bentonite. These mixtures can be used for herbicidal purposes in the dry form, or, by addition of water-soluble surfactants the dry particular solids can be rendered wettable by water so as to obtain stable aqueous dispersions or suspensions suitable for use as sprays. The carrier will be in major proportion and the toxicant, while less than 50% of the composition, will be present in herbicidally effective proportion.

Useful properties as herbicides are illustrated by applying the esters as aqueous sprays to germinating seedlings. The active ingredient was emulsified in water and applied to seeded soil at the rate of 5 pounds per acre. About fourteen days after application of the toxicants results were observed and recorded. The number of seeds emerging was converted to weighted herbicidal ratings based on average percent germination of any particular seed lot times an injury factor. This evened irregularities of herbicide ratings of seeds which varied in percent germination. The injury factor took into consideration any plants not expected to survive. Thus, phytotoxicity ratings were based on the number of plants which emerged and would survive as observed two weeks after planting.

Percent emergence Phytotoxicity rating 6 Formative effects on broadleaved plants were exerted in every case. Furthermore, at 1 pound per acre, ar,ar,artrichlorobenzyl diisopropylcarbamate was severely toxic 3 or severe to a mixture of broadleaved plants, morning glory, sugar 26.50 2 or moderate 5 beets, pigweed and soybean. 2,5-dichlorobenzyl N-ethyl- 51-75 1 or slight. cyclohexanecarbarnate, while phytotoxic, is less effective 76-100 0 or none. than the 2,6-derivative.

TABLE II Toxicant Lbs./ Results Observed Acre ar,ar,ar-Trichlorobenzyl diiso- Severe phytotoxieity to morning glory and propylearbamate. gomtato; moderate phytotoxieity to sugar ee s. ar,ar,ar-Trichlorobenzyl l-piperi- Severe phytotoxicity to morning glory, pigdrnecarboxylate. weed and soybean; moderate phytotoxieity to mixture of broadleaved plants. ar,ar,ar-Trichlorobenzyl 1-pyrrol- Severe phytotoxicity to morning glory, sugar rdrnylearboxylate. beets, pigweed and soybean; moderate phyttotoxieity to mixture of broadleaved p an s. ar,ar,ar-TriehlorobenzylN,N-bis 1 Severe phytotoxieity to mixture of broad- (2ehloroallyl)-earbamate. leaved plants, morning glory, sugar beets,

crab grass, pigweed, soybean, wild buckwheat and tomato; moderate phytotoxieity to radish. ar,ar,ar-Trichlorobenzy1 N-(2- 4 Moderate phytotoxieity to morning glory and chlgroallyl)-eyclohexaneearbapigweed. ma e. ar,ar,ar-Trichlorobenzyl diallyl- Severe phytotoxieity to morning glory and earbamate. pigweed; moderate phytotoxieity to mixture of broadleaved plants and soybean. ar,ar.ar-TriehlorobenzylN-allyl- 1 Severe phytotoxieity to mixture of broadcyclohexaueearbamate. leaved plants, morning glory, sugar beets, crab grass, pigweed and tomato; moderate phytotoxieity to mixture of grasses and rye grass. 2,trdrehlorobenzyl N-ethyleyclo- 2 Severe phytotoxicity to morning glory, hexanecarbamate. brome grass, foxtail, crab grass, pigweed,

Wild buckwheat and sorghum.

The phytotoxicities are recorded below:

TABLE I Toxicant Results Observed ar,ar.ar-Trichlorobenzyl diethylearbamate.

ar,ar,ar-Trichlorobenzyl diisopropylcarbamate.

rolodinylcarboxylate.

ar,ar,ar-Triehlorobenzyl N,N-

bisCZ-chloroallyl) ear'bamate.

ar,ar.ar-Trichlorobenzyl N -(2 clrloroallyl)cyclolrexarrecarbar mate.

ar,ar,arTriehlorobenzyl N,N-

diallylearbamate.

ar,ar,ar-Trielrlorobenzyl N- allylcyclohexane earbamate.

2,6-dichlorobenzyl diethylcarbamate.

2,6 dichlorolenzyl N -ethylcyclohexanecarbamate.

Severe phytotoxicity to morning glory, wild oats, brome grass, rye grass, sugar beets. crab grass, pigweed, soybean, wild buckwheat and tomato; moderate phytotoxicity to radish and barnyard grass.

Severe phytotoxicity to mixture of broadleaved plants, morning glory, sugar beets and pigweed; moderate phytotoxicity to radish, crab grass, wild buckwheat and tomato.

Severe phytotoxieity to mixture of broadleaved plants, morning glory, sugar beets, pigweed, soybean and tomato.

Severe plrytotoxicity to mixture of boradleaved plants, sugar beets, pigweed, soybean and tomato; moderate phytotoxicity to morning glory, brome grass, radish and wild buckwheat.

Severe phytotoxicity to mixture or broadleaved plants, morning glory, sugar beets, pigweed, soybean and tomato; moderate phytotoxieity to mixture of grasses, brome grass, radish and crab grass.

Severe phytotoxicity to morning glory sugar beets and pigweed; moderate phytotoxicity to mixture of broadleaved plants, rad ish and crab grass.

Severe phytotoxieity to mixture of broadleaved plants, morning glory, sugar beets, pigweed, soybean and tomato; moderate phytotoxicity to radish.

Severe phytotoxieity to morning glory and pigweed; moderate phytotoxicity to mixture or broadleaved plants.

Severe phytotoxieity to (lab grass, pigweetl, soybean and tomato; moderate phytotoxieity to morning glory, wild oats, sugar beets, barnyard grass, wild buckwheat and sorghum.

Severe phytotoxicity to morning glory, brome grass, sugar beets and crab grass; moderate phytotoxicity to mixture of grasses and foxtail. Chlorosis-grass.

Greater efilciency than from surface application results from incorporating the toxicants into the top layer of soil. Phytotoxicity ratings observed by incorporating the esters into the surface soil are recorded above.

For the compounding of mineral oils the new compounds are preferably incorporated in amounts of 1 to 10%. In most cases the compounds are completely miscible in all proportions and mineral oil concentrates may be prepared.

The term surfactant as employed in the specification and in the appended claims is used as in volume II of Schwartz, Perry and Berchs Surface Active Agents and Detergents (1958, Interscience Publishers, Inc., New York), in place of the expression emulsifying agent to connote generically the various emulsifying agents, dispersing agents, wetting agents and spreading agents that are adapted to be admixed with the active compounds of this invention in order to secure better wetting and spreading of the compound in water vehicle or carrier in which it is insoluble through lowering the surface tension of the water (see also Frear, Chemistry of Insecticides, Fungicides and Herbicides, second edition, page 280). These surfactants include the well-known capillary-active substances which may be anion-active (or anionic), cation active (or cationic), or non-ionizing (or non-ionic), which are described in detail in Volumes I and II of Schwartz, Perry and Berchs Surface Active Agents and Detergents (1958, Interscience Publishers, Inc., New York) and also in the November, 1947 issue of Chemical Industries (pages 811-824) in an article entitled Synthetic Detergents by John W. McCutcheon and also in the July, August, September and October 1952 issues of Soap and Sanitary Chemicals under the title Synthetic Detergents. The preferred surfactants are the watersoluble anionic surface-active agents and the water-soluble non-ionic surface-active agents set forth in U.S. 2,846,398 (issued Aug. 5, 1958). In general it is preferred that a mixture of water-soluble anionic and water-soluble nonionic surfactants be employed.

It is intended to cover all changes and modifications of the examples of the invention herein chosen for purposes @cm-o-out where X is halogen, n is an integer which is one of 2 and 3 and R is selected from the group consisting of disubstituted NH radicals wherein the substituents are selected from the group consisting of lower alkyl, alkoxy substituted lower alkyl, lower olefinic, halogen substituted lower olefinic and cyclohexyl radicals with the proviso that not more than one is cyclohexyl and organic nitrogen containing heterocyclic radicals derived from amines of the group consisting of pyrrolidine, piperidine, Z-methyI-I-piperidine, 5 ethyl 2 methyl 1 piperidine, 5 ethyl 3 methyll-piperidine, 2,4,6-trimethyl-l-piperidine and hexamethylenimine.

2. The method of claim 1 in which the ester is applied to the ground before the plants emerge.

3. The method of destroying undesired vegetation which comprises applying thereto a phytotoxic concentration of a halobenzyl ester of a disubstituted carbamic acid of the structure where A and A are lower alkyl groups.

4. The method of destroying undesired vegetation which comprises applying thereto a phytotoxic concentration of a 2,6-dichloro substituted benzyl ester of a di(lower alkyl) carbamic acid.

5. The method of destroying undesired vegetation which comprises applying thereto a phytotoxic concentration of a 2,5-dichloro substituted benzyl ester of a di(lower alkyl) carbamic acid.

6. A herbicidal composition comprising a majorproportion of herbicidal adjuvant as carrier and a minor but herbicidally effective proportion of a halobenzyl ester of a disubstituted carbamic acid of the structure where X is halogen, n is an integer which is one of 2 and 3 and R is selected from the group consisting of disubstituted NH radicals wherein the substituents are selected from the group consisting of lower alkyl, alkoxy substituted lower alkyl, lower olefinic, halogen substituted lower olefinic and cyclohexyl radicals with the proviso that not more than one is cyclohexyl and organic nitrogen containing heterocyclic radicals derived from amines of the group consisting of pyrrolidine, piperidine, Z-methyl-lpiperidine, 5 ethyl 2 methyl 1 piperidine, 5 ethyl- 3-methyl-1-piperidine, 2,4,6-tri-methyl-l-piperidine and hexamethylenimine, in intimate admixture with a surfactant.

References Cited UNITED STATES PATENTS 2,812,247 11/1957 Gysin et al. 71-2.3 2,992,091 7/1961 Harmon et al 71-2.5 X 3,078,153 2/1963 Harmon et al. 71-25 LEWIS GOTTS, Primary Examiner.

JAMES O. THOMAS, 1a., Examiner. 

1. THE METHOD OF DESTROYING UNDESIRED VEGETATION WHICH COMPRISES APPLYING THERETO A PHYTOTOXIC CONCENTRATION OF A HALOBENZYL ESTER OF A DISUBSTITUTED CARBAMIC ACID OF THE STRUCTURE 